A conventional regional energy supply system provided with natural energy electric power generation equipment using natural energy such as wind power, solar power, etc., has a distributed power supply device with a storage battery for eliminating the instability of power supply due to frequent output fluctuations thereof, and includes an optimum system operation planning section that creates an optimum operation plan of the distributed power supply device, and a control command value decision section that stores an amount of accumulated or stored electricity (electric power) and the cost for accumulating or storing electricity (electric power) by measuring and summing the amount of charge and discharge and the charging cost of the storage battery, wherein when it is determined, by the calculation of simulating the cases when the amount of charge and discharge of the storage battery is increased or decreased, that the sum of an amount of variation of the cost of buying and selling electric power due to the transmission (receiving and sending) thereof with an electric power system and an amount of variation of the charging cost due to the amount of charge and discharge of the storage battery becomes negative, the control command value decision section changes a control command value for the amount of charge and discharge of the storage battery in the process of the optimum operation plan, and sends it to the distributed power supply device (see, for example, a first patent document).    First Patent Document Japanese patent application laid-open No. 2005-143218